The long range goal of this work is to obtain a better understanding of molecular evolution as it applies to oligomeric enzymes. The structural and catalytic relationships of four enzymes (3-aminopropanal, 4-aminobutanal, NAD ion-succinic semialdehyde, and NADP ion-succinic semialdehyde dehydrogenases) are being investigated. Kinetic, Chemical, amd Immunochemical methods are being used to study the divergence of these tumeric enzymes from a common ancestral protein. The subunit hybrids of some of these enzymes are also being used to study the effects of hybridization on structure, catalysis, and antigenicity.